Development of software products commonly proceeds in phases or iterations. Each phase or iteration may require different types of changes to be made to the product, may involve different personnel assigned to different activities, and may be characterized by different context conditions. The personnel involved in the development may be characterized by different levels of expertise and prior experience, but may also differ in terms of physiological and psychological preferences and sensitivities. Context conditions may influence the physiological and psychological states and behaviors of the personnel in accordance with their individual preferences and sensitivities. As a result, enduring characteristics of the individual worker, the changing state and actions of the worker, and the characteristics of the product changes that are carried out, together influence the expected product and project outcomes of a development phase or iteration as well as of the product and project lifecycle.